Learning Haskell with Chess
This page is about learning Haskell using the board game Chess as a running example. The complete code can be found at http://www.steffen-mazanek.de/dateien/projekte/hsChess.zip. @German Haskellers: You may also have a look at the tex-files used in our student exercises, http://www.steffen-mazanek.de/dateien/projekte/hsChess-teaching-german.zip.
Exercise 1 - data types
- recapitulate Haskell types (keywords
data, product and sum types)
- Helium: equality and show functions (pattern matching)
- Haskell: type classes (
- list handling (boards will be represented by lists of lists)
- Define data types that represent boards (
Board), squares (
Square), positions (
Pos), pieces (
Piece, supported by
PieceType) and game states (
- Helium: Implement suited eq and show functions.
- Haskell: Define/derive instances of
- Implement a function
prettyBoard::Board->String, that transforms a board into a clearly arranged string representation (human readable :-)). Support this function with auxiliary functions that pretty print pieces, squares, ...
- Define the initial board (
- Implement a simple evaluation function
evalBoard::Board->Intas the difference of material on board, for this purpose define a function
valuePiecethat maps pieces to their values (pawn->1, knight and bishop->3, queen->9, rook->5, king->"infinity"=1000).
Exercise 2 - move generator
- list comprehension
- stepwise refinement
Exercise 3 - gametree generation and minimax algorithm
- break code in modules
- recursive data structures -> recursive algorithms
- Define a data type that represents a game tree (
- Roughly estimate the number of nodes of the gametree with depth 4.
- Define a function
play::Gametree->Int, that computes the value of a given game tree using the minimax Algorithm.
- Implement the function
doMove::State->State, that choses the (best) next state.